1. Field of the Invention
This invention relates to a high frequency amplifier including a transistor on a multi-layer printed-circuit board and a shielding circuit for amplifying an input signal and a radio wave transmission apparatus including the same.
2. Description of the Prior Art
A high frequency amplifier including multi-stages of transistors on a multi-layer printed-circuit board and a guard circuit for amplifying an input signal is known. Japanese patent application provisional publication No. 5-37253 discloses such a prior art high frequency amplifier. Coupling between two consecutive stages are reduced by a ground circuit pattern or by a capacitor of which electrode is grounded.
FIG. 5 is a plan view of a first prior art high frequency power amplifier disclosed in Japanese patent application provisional publication No. 5-37253. In FIG. 5, coupling between two consecutive stages are reduced by a ground circuit pattern 302A provided therebetween.
FIG. 6 is a plan view of a second prior art high frequency power amplifier disclosed in Japanese patent application provisional publication No. 5-37253. In FIG. 6, coupling between two consecutive stages are reduced by a capacitor C1 of which one electrode is grounded.